Former President Bill Clinton will headline a fundraiser for U.S. Sen. Mark Udall during a luncheon in Denver on Sept. 27, the senator’s campaign confirmed.

Udall faces a tough challenge from Republican Congressman Cory Gardner, who was down only 4 percentage points against Udall and within the margin of error in a Denver Post poll released Thursday.

“Bill Clinton remains the top draw for Democratic candidates seeking to pad their treasuries and boost their poll numbers,” according to Bloomberg News, which first reported the visit.

“It’s a role the former president has become accustomed to in recent years, as he’s criss-crossed the country to assist Democratic candidates ranging from Obama to U.S. House, Senate and state-level candidates. At times, he’s picked sides in Democratic primaries, backing those who supported Hillary Clinton in her 2008 campaign against candidates who endorsed Obama. Udall waited until the 2008 primary race was over to endorse Obama,” Bloomberg reported.

Conservation Colorado, a political nonprofit that advocates for environmental policies, spent more than $4.6 million -- a record for the group — to help Democrats take the levers of state government this month.

Denver police have increasingly focused curfew enforcement in Latino neighborhoods in recent years — with a special emphasis on Cinco de Mayo and other holidays — while other areas have seen much less enforcement.